to get a full metal soud from dynatube, i used the MB cab+speaker, vinco as pre-insert and, as a post-insert, the "tube-strip" (free device in device section) with almost all the "tube drives" at maximum and a bit of shape with the EQ.
then, try to add a bit of reverb and, perhaps, a delay set with short time (30-80 msec), high feedback and low wet signal to achieve a sort of "spring" sound....